From 3a45d10632fc6041c6a6790a3c4b03b3f9536dad Mon Sep 17 00:00:00 2001 From: Matthijs Kooijman Date: Wed, 7 Apr 2010 15:12:03 +0200 Subject: [PATCH] Add non-representable result inlining transformation. --- "c\316\273ash/CLasH/Normalize.hs" | 93 ++++++++++++++++++++++++++++++- 1 file changed, 92 insertions(+), 1 deletion(-) diff --git "a/c\316\273ash/CLasH/Normalize.hs" "b/c\316\273ash/CLasH/Normalize.hs" index 9f75470..cd205c6 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -20,7 +20,9 @@ import qualified Data.Map as Map -- GHC API import CoreSyn import qualified CoreUtils +import qualified BasicTypes import qualified Type +import qualified TysWiredIn import qualified Id import qualified Var import qualified Name @@ -777,6 +779,95 @@ argprop c expr = return expr -- Perform this transform everywhere argproptop = everywhere ("argprop", argprop) +-------------------------------- +-- Non-representable result inlining +-------------------------------- +-- This transformation takes a function that has a non-representable +-- result (e.g., a tuple containing a function, or an Integer. The +-- latter can occur in some cases as the result of the fromIntegerT +-- function) and inlines enough of the function to make the result +-- representable again. +-- +-- This is done by first normalizing the function and then "inlining" +-- the result. Since no unrepresentable let bindings are allowed in +-- normal form, we can be sure that all free variables of the result +-- expression will be representable (Note that we probably can't +-- guarantee that all representable parts of the expression will be free +-- variables, so we might inline more than strictly needed). +-- +-- The new function result will be a tuple containing all free variables +-- of the old result, so the old result can be rebuild at the caller. +inlinenonrepresult, inlinenonrepresulttop :: Transform + +-- Apply to any (application of) a reference to a top level function +-- that is fully applied (i.e., dos not have a function type) but is not +-- representable. We apply in any context, since non-representable +-- expressions are generally left alone and can occur anywhere. +inlinenonrepresult context expr | not (is_fun expr) = + case collectArgs expr of + (Var f, args) -> do + repr <- isRepr expr + if not repr + then do + body_maybe <- Trans.lift $ getNormalized_maybe True f + case body_maybe of + Just body -> do + let (bndrs, binds, res) = splitNormalizedNonRep body + -- Get the free local variables of res + global_bndrs <- Trans.lift getGlobalBinders + let interesting var = Var.isLocalVar var && (var `notElem` global_bndrs) + let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting res + let free_var_types = map Id.idType free_vars + let n_free_vars = length free_vars + -- Get a tuple datacon to wrap around the free variables + let fvs_datacon = TysWiredIn.tupleCon BasicTypes.Boxed n_free_vars + let fvs_datacon_id = DataCon.dataConWorkId fvs_datacon + -- Let the function now return a tuple with references to + -- all free variables of the old return value. First pass + -- all the types of the variables, since tuple + -- constructors are polymorphic. + let newres = mkApps (Var fvs_datacon_id) (map Type free_var_types ++ map Var free_vars) + -- Recreate the function body with the changed return value + let newbody = mkLams bndrs (Let (Rec binds) newres) + -- Create the new function + f' <- Trans.lift $ mkFunction f newbody + trace ("New body: " ++ pprString newbody) $ return () + trace ("Function type" ++ (pprString $ Id.idType f')) $ return () + + -- Call the new function + let newapp = mkApps (Var f') args + res_bndr <- Trans.lift $ mkBinderFor newapp "res" + -- Create extractor case expressions to extract each of the + -- free variables from the tuple. + sel_cases <- Trans.lift $ mapM (mkSelCase (Var res_bndr)) [0..n_free_vars-1] + + -- Bind the res_bndr to the result of the new application + -- and each of the free variables to the corresponding + -- selector case. Replace the let body with the original + -- body of the called function (which can still access all + -- of its free variables, from the let). + let binds = (res_bndr, newapp):(zip free_vars sel_cases) + let letexpr = Let (Rec binds) res + + -- Finally, regenarate all uniques in the new expression, + -- since the free variables could otherwise become + -- duplicated. It is not strictly necessary to regenerate + -- res, since we're moving that expression, but it won't + -- hurt. + letexpr_uniqued <- Trans.lift $ genUniques letexpr + change letexpr_uniqued + Nothing -> return expr + else + -- Don't touch representable expressions + return expr + -- Not a reference to or application of a top level function + _ -> return expr +-- Leave all other expressions unchanged +inlinenonrepresult c expr = return expr +-- Perform this transform everywhere +inlinenonrepresulttop = everywhere ("inlinenonrepresult", inlinenonrepresult) + + -------------------------------- -- Function-typed argument extraction -------------------------------- @@ -836,7 +927,7 @@ funextracttop = everywhere ("funextract", funextract) -- What transforms to run? -transforms = [inlinedicttop, inlinetopleveltop, knowncasetop, classopresolutiontop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letrectop, letremovetop, retvalsimpltop, letflattop, scrutsimpltop, scrutbndrremovetop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop] +transforms = [inlinedicttop, inlinetopleveltop, inlinenonrepresulttop, knowncasetop, classopresolutiontop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letrectop, letremovetop, retvalsimpltop, letflattop, scrutsimpltop, scrutbndrremovetop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop] -- | Returns the normalized version of the given function, or an error -- if it is not a known global binder. -- 2.30.2